LOANS AND ALLOWANCE FOR CREDIT LOSSES - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 15,874,258,000	$ 14,480,925,000	$ 12,818,476,000
Financing receivable, nonaccrual, interest income	0
Balance	52,078,000	123,082,000
Financing receivable, nonaccrual	85,266,000	76,457,000
Loans modified that are not troubled debt restructurings	408,900,000	436,000,000
Troubled debt restructurings excluding purchased loans	76,600,000	85,000,000
Troubled debt restructurings, previous charge-offs	654,000	1,200,000
COVID-19 Deferrals	41,725,000	332,779,000
Proceeds from sales of other loans held for sale	156,803,000	0	0
Loans charged off	21,616,000	54,464,000	19,861,000
Loans held for sale	1,254,632,000	1,167,659,000
Release of provision for loan losses	35,081,000	(125,488,000)	(19,758,000)
Real estate – commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	6,834,917,000	5,300,006,000	4,353,039,000
Balance	33,332,000	100,180,000
Financing receivable, nonaccrual	15,365,000	18,517,000
COVID-19 Deferrals	1,899,000	179,183,000
Loans charged off	1,852,000	27,504,000	3,342,000
Release of provision for loan losses	9,784,000	(78,210,000)	(3,017,000)
Consumer installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	191,298,000	306,995,000	498,577,000
Financing receivable, nonaccrual	476,000	709,000
COVID-19 Deferrals	0	1,418,000
Loans charged off	6,248,000	5,642,000	5,899,000
Release of provision for loan losses	(7,330,000)	3,831,000	(4,268,000)
Commercial, financial and agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	1,875,993,000	1,627,477,000	802,171,000
Balance	2,613,000	5,490,000
Financing receivable, nonaccrual	14,214,000	9,836,000
COVID-19 Deferrals	1,430,000	12,471,000
Loans charged off	7,760,000	10,647,000	3,460,000
Release of provision for loan losses	(12,071,000)	(8,963,000)	(3,837,000)
Loans Excluding Purchased Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructuring loans	19,661,000	49,381,000
Allowance for loan losses allocated to troubled debt restructurings	10,500,000	13,000,000
Loans Excluding Purchased Loan | Real estate – commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructuring loans	16,197,000	31,630,000
Loans Excluding Purchased Loan | Consumer installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructuring loans	7,000	15,000
Loans Excluding Purchased Loan | Commercial, financial and agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructuring loans	401,000	855,000
Loans Excluding Purchased Loan | Financing Receivables, 1 to 29 Days Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructuring loans	2,292,000	4,378,000
Loans Excluding Purchased Loan | Financing Receivables, 1 to 29 Days Past Due | Real estate – commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructuring loans	0	929,000
Loans Excluding Purchased Loan | Financing Receivables, 1 to 29 Days Past Due | Consumer installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructuring loans	5,000	2,000
Loans Excluding Purchased Loan | Financing Receivables, 1 to 29 Days Past Due | Commercial, financial and agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Troubled debt restructuring loans	35,000	2,000
Hotel Loans | Real estate – commercial and farmland
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sales of other loans held for sale		87,500,000
Loans charged off		17,200,000
Loss on sale of loans		386,000
Held For Sale Loans | Consumer installment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans charged off		1,600,000
Loans held for sale		165,900,000
Release of provision for loan losses		6,700,000
PPP Loans | Commercial, financial and agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net of unearned income	$ 127,800,000	$ 827,400,000
Minimum | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, nonaccrual			100,000
Troubled debt restructuring loans			$ 100,000